Hearing aid



FIG. 1 is a side elevational view of a hearing aid showing my newdesign;

FIG. 2 is a side elevational view thereof, taken from the left of FIG.1;

FIG. 3 is a side elevational view thereof, taken from the right of FIG.1;

FIG. 4 is a top plan view thereof; and

FIG. 5 is a bottom plan view thereof.

The ornamental design for a hearing aid, as shown and described.